P4mm Symmetry Research Articles

Effect of Rare Earth doping on Structural, Morphological, Optical, and Magnetic Properties of the Y1-x(Gd, Dy)xBaCuFeO5+δ (x = 0.2, 0.4, 0.6, and 0.8) Ceramics

The effect of the rare earth (RE) ion substitution on the structural, morphological, optical and magnetic properties of the Y1-xRExBaCuFeO5 (RE = Gd, Dy; x = 0.2, 0.4, 0.6, and 0.8) multiferroic compounds grown by the solid-state reaction is evaluated using X-ray diffraction (XRD), scanning electron microscopy (SEM), dispersive X-ray spectroscopy (EDX), reflectance spectroscopy techniques diffuse (UV-vis-NIR) and vibrating sample magnetometry (VSM). The results indicate that the RE substitution led to growth of single-phase materials, with a tetragonal structure and P4mm symmetry. The morphological analysis shows the formation of polycrystalline materials composed of grains of various shapes and sizes. Furthermore, the compositional analysis reveals that the materials do not present elements other than those used in the synthesis. The band gap (Eg) is tuned from 0.88 to 0.90 eV upon RE substitution. The magnetization curves obtained in the Zero-Field-Cooled/Field-Cooled (ZFC-FC) modes between 50 and 390 K, reveal a paramagnetic behavior, which could be attributed to the dominance exerted by the magnetic moments of the Gd/Dy ions.

Comparing the compression behavior of the antiperovskites CePt3Si, CePt3B, and YPt3B from combined X-ray diffraction experiments and density functional theory

In this study we report the synthesis three antiperovskites YPt3B, CePt3B, and CePt3Si as well a focused investigation of YPt3B, which all have the same P4mm symmetry with a large c∕a ratio at ambient conditions. The compounds are investigated under high-pressure using powder X-ray diffraction in diamond anvil cells. A structural transition is found to occur in the YPt3B compound at 23(2) GPa caused by the softening of a zone boundary phonon. Using a combination of symmetry analysis and structural prediction, the high-pressure phase is assigned to a structure described by the P2 (P121) space group. Calculation of the phonon dispersion confirms that this structure is dynamically stable with A = Ce, Y and Z = Si, B. It was found that the three APt3Z compounds behave differently with pressure. The bulk moduli for the three compounds are found to be 185(5) GPa, 155(3) GPa, and 128(2) GPa for YPt3B, CePt3B, and CePt3Si, respectively. We found that the Z atom moves away from the center with pressure for A = Ce along the c axis, whereas for A = Y, the Z atom stays in the approximately same position. This behavior is also reflected in their c∕a ratio which stays approximately constant in YPt3B. Overall we find that the Ce-bearing compounds are more compressible in the ab plane, reducing the tilting of the octahedra. As a result, in YPt3B and CePt3B the transition to the structure described by the P2 space group is likely to occur at higher pressures.

Enhanced dielectric and electrical properties of Ba(1−x)Nd2x∕3Zr0.1Ti0.9O3 (0.00 ≤ x ≤ 0.04) electroceramics for high temperature-based energy storage devices

The demand for high-temperature endurable dielectric materials with higher thermal stability in electronic systems operating under extreme temperatures sets a significant channel for the electronic industry. This work focuses on the dielectric and impedance behavior for lead-free Ba1−xNd2x∕3Zr0.1Ti0.9O3 (BNZT); (0.00 ≤x≤ 0.04) between 300 ∘C – 400 ∘C and synthesized by conventional solid-state reaction method at optimum temperatures. Structural characterizations confirmed the tetragonal (P4mm symmetry) structure formations for the BNZT ceramics. XPS analysis confirmed the Nd-substitution at the Ba-site in the BNZT ceramics. FE-SEM study showed grain growth reduction with enhanced grain boundaries. The dielectric study showed lower dielectric loss with enhanced dielectric permittivity at high temperatures. Impedance analysis confirmed the negative temperature coefficient of resistance (NTCR) and non-Debye type behavior with higher thermal stability. Singly-ionized oxygen vacancies mainly govern the conduction process in BNZT ceramics. Enhanced dielectric and impedance properties suggest that Nd-substituted BNZT electroceramics are promising materials for applications in high-temperature-based energy storage systems.

First-principles calculation to investigate structural, electronic, optical, and thermodynamics properties of perovskite KXO3 (K[dbnd]Ta and Zn) alloys for photovoltaic and smart window applications

Compounds KXO3 (X = Zn and Ta) properties are explored using CASTEP (Cambridge serial total energy package) software along with Generalized Gradient Approximation (GGE) and PBE exchange-correlation functionals that have pm3m (221) symmetry with cubic. Electronic characteristics associated with the electronic band structure (phase), total density of states TDOS, partial DOS, and elemental PDOS have been calculated. KTaO3 and KZnO3 show an indirect energy bandgap of 1.61 eV and 4.53 eV, respectively; thus, KTaO3 is a semiconductor while KZnO3 is an insulator. Optical properties disclose that maximum absorption occurs in both visible and ultra-violet ranges of the electromagnetic (EM) spectrum of KTaO3 and KZnO3. The elastic properties of the compounds show that KTaO3 is ductile and KZnO3 is brittle, and the brittleness of the compound will increase the reflection of the radiation, and KTaO3 will conduct radiation more frequently in the visible region.

Structural, Microstructural, and Electrical Properties Study of Pb(Sn0.45Ti0.55)O3 Ceramics

We undertook a comprehensive investigation of the the structural, dielectric, and electrical characteristics of Pb(Sn0.45Ti0.55)O3 ceramics prepared using the conventional solid-state route. A meticulous preparation protocol, involving solvating various precursors, was followed by extensive characterization employing X-ray diffraction, scanning electron microscopy, and dielectric studies. The synthesized sample features a single-phase tetragonal structure with P4mm symmetry. Using impedance spectroscopy, electrical transport properties of the polycrystalline Pb(Sn0.45Ti0.55)O3(PST) ceramic were studied in detail. Relaxation and conduction mechanisms of the material were inferred using complex impedance, complex electric modulus, and frequency dependent ac conductivity analysis. Impedance spectroscopy results reveal the range of frequencies in which the grain, grain boundary, and electrode effects are dominant. Above certain temperatures, the imaginary component of impedance (Z//) exhibits some resonant type peaks at different frequencies indicating relaxor nature of the sample. The activation energy obtained for both the relaxation and conduction process indicates the role of doubly-ionized oxygen vacancy in the conduction mechanism of the sample. The dielectric relaxation occurring at low frequency and high temperatures is related to the space charges associated with the ionized oxygen vacancies being trapped at the grain boundaries. The Cole-Cole plots confirm the poly-dispersive nature of dielectric relaxation in the sample.

Optimizing energy storage under low electric field in A-site dysprosium modified BiFeO3-BaTiO3 ceramics

Electric recoverable energy density and dielectric breakdown strength are crucial factors in the high power-density capacitors. This study highlights the A-site dysprosium (Dy) substituted perovskite 0.5(Bi1−xDyx)FeO3-0.5BaTiO3 relaxor ferroelectric ceramics (x = 0–0.30) in O2-atmosphere sintering. An overall pseudo-cubic structure with a major cubic Pm-3m symmetry was observed in all compositions accompanied by multiple lattice symmetries. Anti-polar orthorhombic Pbam space group and non-polar orthorhombic Pnma symmetry gradually increase while ferroelectric tetragonal P4mm symmetry decreases as Dy content approaches x = 0.3. Recoverable energy densities (Wrec) of 4.8 J/cm3 and 3.6 J/cm3, storing efficiencies (η) of 68% and 75%, and recoverable energy storage intensities (ρ) of ∼3.2×10−2 J/kV·cm2 and ∼2.1×10−2 J/kV·cm2 were attained at x = 0 and 0.10 at electric fields of 150 and 175 kV/cm, respectively. The breakdown strength is improved from 150 to 200 kV/cm as x increases from 0.0 to 0.30. This study suggests that grain boundaries and local nanoclusters may act as barriers to inhibit charge transport and consequently increase the breakdown strength.

Cu and Er modified barium zirconium titanate (BaZr0.05Ti0.95O3) ceramics: Composition-dependent dielectric properties

Cu2+ and Er3+ doped BaZr0.05Ti0.95O3 (BZT) ceramics were prepared using the solid-state reaction method, where amount of CuO + Er2O3 was fixed at 2 wt.% and different CuO : Er2O3 molar ratios (i.e. 1:1, 1:2, 1:3, 2:1 and 3:1) were used. The influence of Cu2+ and Er3+ doping on crystal structure and dielectric properties of the samples sintered at 1300 ?C was investigated. X-ray diffraction analysis confirmed the formation of a single-phase material and tetragonal crystal structure with P4mm symmetry. Microstructural analysis conducted with a scanning electron microscope revealed well-defined and uniformly distributed grains across the surface of the sintered samples and reduction of grain size and density with doping. The highest energy storage density of 40.51mJ/cm3 with an energy efficiency of 78.8% was obtained in the sample with CuO : Er2O3 molar ratio of 2:1. The doped BZT ceramics have high dielectric constant and significantly lower tangent loss in comparison to the undoped BZT. The dielectric data confirm the non-Debye behaviour for all the samples. Impedance spectroscopy and electrical modulus analysis indicated that conduction in the materials was influenced by both the grains and grain boundaries. The AC conductivity is described by the Jonscher?s universal power law, whereas DC conductivity follows a dependency based on the Arrhenius?s theory. The results revealed a conduction mechanism characterized by non-overlapping small Polaron tunnelling up to 340?C and a transition to correlated barrier hopping conduction above 340?C within the selected temperature range for all the samples. According to the Arrhenius fitting of DC conductivity the activation energy of the undoped BaZr0.05Ti0.95O3 sample is 0.168 eV and decrease with doping to 0.138 and 0.131 eV for the sample with lower Cu2+ contents (CuO : Er2O3 molar ratios of 1:2 and 1:3, respectively).

Structural, optical, dielectric, and ferroelectric properties in [formula omitted] ceramics prepared by a solvothermal reflux approach

Chromium (Cr3+) doped BaTi1−xCrxO3 (x = 0.0, 0.03, 0.06, and 0.09) ceramics were prepared by the solvothermal reflux approach. X-ray diffraction analysis confirmed the development of tetragonal structures with P4mm symmetry in the prepared samples. The SEM analysis showed that Cr3+ doping resulted in a microstructure that was dense, uniform, and had smaller grains. Surface chemical information and oxidation states were studied using X-ray photoelectron spectroscopy. The diffuse reflectance spectrum confirmed the effect of Cr3+ content on the direct optical bandgap of BaTi1−xCrxO3 samples which shifts from 3.21 eV to 2.73 eV with increasing Cr3+ content. Dielectric permittivity was found to increase in the low-frequency region with increasing Cr3+ doping content up to x = 0.06, while it decreased in the high-frequency region compared to an undoped sample. The observed behavior of permittivity might be explained in terms of the formation of oxygen vacancy defects and their effects on the polarization dynamics of the material. Moreover, the addition of Cr3+ doping had a strong effect on the ferroelectric characteristics, as seen by the formation of a pinched hysteresis loop, resulting in the improvement of energy storage properties. Based on the obtained results, the sample with x = 0.06 exhibited an enhancement of about 3.3 times in energy discharge density and 26 % in storage efficiency compared to the undoped sample. This might be due to a large difference between the values of maximum and remnant polarizations, reduced tangent loss, and a smaller grain size, which makes this material attractive for use in energy storage devices.

Structure, dielectric and ferroelectric Properties of (1-x)K0.5Na0.5NbO3 – xBi0.5Na0.5TiO3(0 ≤ x≤ 0.1) Solid Solution

In this study, we prepared lead-free (1-x)K0.5Na0.5NbO3 – xBi0.5Na0.5TiO3 ceramics (KNNBTx) with x = 0, 0.025, 0.05, 0.075, 0.1 using the conventional solid-state reaction method. Scanning electron microscopy analysis revealed dense ceramics with a notable decrease of the average grain size from 3 μm for x = 0–0.3 μm for x ≥ 0.050. X-ray diffraction pattern refinement unveiled that the pure KNN possessed an orthorhombic Amm2 symmetry. In contrast, the KNNBT0.100 composition displayed a tetragonal P4mm symmetry, while the KNNBT0.025 composition exhibited a monoclinic Pm symmetry, suggesting the stabilization of an intermediate phase between the orthorhombic and tetragonal symmetries for x = 0.025. Dielectric measurements indicated that the introduction of small cations in A and B sites of the KNN matrix induced a diffusive phase transition. According to the modified Curie–Weiss law (named also Uchino and Nomura function), the degree of diffuseness (γ) increased from γ = 1.45 to γ 1.74 with increasing x. Raman spectroscopy revealed a frequency upshift of the vibration modes along with broadening of the modes as the NBT composition increased, indicating increased structural disorder in the perovskite structure. Temperature-dependent Raman spectra exhibited the persistence of certain modes at higher temperatures due to the off-centering of cations at A and B sites, a result of the induced substitution-induced disorder in the KNN matrix. Temperature dependent of Raman modes’ frequency have shown substantial modifications at temperatures close to the critical temperatures identified by dielectric measurements. Ferroelectric measurements demonstrated that the incorporation of NBT into the KNN matrix led to significant alterations in the polarization and ferroelectric characteristics of the parent ceramic (pure KNN). As the NBT content increased, the remanent polarization decreased from 13.1 to 3.6 μC/cm2, and the P-E curves became pinched/distorted, indicating a disruption in the long-range order of KNN due to structural and grain size modifications.

Insight of the Influence of Cobalt Substitution on the Structural, Microstructural, Optical and Electrical Properties of Tetragonal Barium Titanate Ceramics

The development of lead-free ferroelectric materials is essential for upcoming applications in energy and information storage. We comprehensively report the structural, optical, dielectric and electrical characteristics of BaTi1-x Co x O3 (0.00 ≤ x ≤ 0.10) ceramics prepared using the conventional solid-state route process. The synthesized sample features a single-phase tetragonal structure with P4mm symmetry, as confirmed by the X-ray diffraction investigation. SEM imaging clearly shows that the material was polydispersive. UV–vis diffuse reflectance spectra of the BaTi1-xCoxO3 ceramics has been carried out in order to calculate the optical band gap of each composition. For the prepared samples, Cole-Cole plot of the complex impedance was examined over a wide temperature and frequency range. The compounds displayed non-Debye type dielectric relaxation. The Ferroelectric-Paraelectric phase transition is clearly visible in the T-dependent dielectric spectra for all the samples. After E-poling the ceramics, a well-defined genuine saturated hysteresis loop was established.

Strain-Induced Structural Phase Transitions in Epitaxial (001) BiCoO3 Films: A First-Principles Study.

We have simulated BiCoO3 films epitaxially grown along (001) direction with density functional theory computations. Leading candidates for the lowest-energy phases have been identified. The tensile strains induce magnetic phase transition in the ground state (P4mm symmetry) from a C-type antiferromagnetic order to a G-type order for the in-plane lattice parameter above 3.922 Å. The G-type antiferromagnetic order will be maintained with larger tensile strains; however, a continuous structural phase transition will occur, combining the ferroelectric and antiferrodistortive modes. In particular, the larger tensile strain allows an isostructural transition, the so-called Cowley's ''Type Zero'' phase transitions, from Cc-(I) to Cc-(II), with a slight volume collapse. The orientation of ferroelectric polarization changes from the out-of-plane direction in the P4mm to the in-plane direction in the Pmc21 state under epitaxial tensile strain; meanwhile, the magnetic ordering temperature TN can be strikingly affected by the variation of misfit strain.

High pressure effects on ferroelectric tetragonal phase in BaTi1−xFexO3 (x=1%)

The pressure-driven phase transformation in polycrystalline BaTi[Formula: see text]FexO3 ([Formula: see text]%), synthesized by a solid-state reaction method, was investigated using synchrotron X-ray diffraction and Raman spectroscopy. All measurements were performed at room temperature within a large pressure range up to 36.5 GPa. The results clearly demonstrate a phase transformation from the ferroelectric tetragonal structure of P4mm symmetry to the paraelectric cubic structure of Pm-3m symmetry in the studied sample at the pressure of about 18 GPa. This phase transformation pressure is much higher than those previously reported for BaTiO3-based systems, indicating the stabilization of the ferroelectric phase by doping 1% Fe into BaTiO3. Feature modes of the tetragonal phase still persist while some new modes appear in the Raman spectra at pressures above 18 GPa. This is probably due to accumulated stress and/or local microscopic disorders in the sample, which are associated with the displacement of the Ti atoms along unit-cell diagonals.

The magnetic ground state of Ba(Fe1/2Sn1/2)O3-δ: A potential giant dielectric material for technological applications

Ba(Fe1/2Sn1/2)O3-δ (BFSO) is a potential environmental friendly compound for miniaturization of electronic devices as it exhibits giant dielectric constant at room temperature. However, its magnetic ground state is not settled. We present here comprehensive investigation of the as-sintered and oxygen-annealed BFSO samples using x-ray diffraction, dielectric, x-ray photoelectron spectroscopy (XPS), dc magnetization (M(T, H, t)) and specific heat measurements. Both samples crystallize in a cubic Pm-3m symmetry. At room temperature, both samples show a giant dielectric constant of the order of ε' ∼104 and two low-temperature dielectric relaxations resulting from polaron-hoping and Maxwell-Wagner effect, respectively. The temperature-dependent dc magnetization and specific heat measurements on as-sintered and oxygen-annealed BFSO samples confirm the absence of long-range ordered antiferromagnetic transition at TN ∼55 K. Further, both samples show history-dependent irreversibility of zero-field cooled warming (ZFCW) and field cooled warming (FCW) M(T) curves at the irreversibility temperature (Tirr ∼18 K) with a peak in the ZFCW M(T) curve at the spin-glass freezing temperature Tf ∼16 K. In addition, the FCW M(T) curve of both samples show plateauing over a small temperature range before it starts increasing below Tf, a characteristic typically observed in cluster/spin-glass systems. The presence of long-time magnetic relaxation and aging effect in both samples further support the spin-glass behavior. We also discussed the impact of oxygen vacancies on the physical and magnetic properties and possible origin of the glassy ground state in BFSO.

High-efficiency energy storage in Nd-doped (1-x)BiFeO3–xBaTiO3 relaxor ferroelectric ceramics

Dielectric capacitors as energy storage electronics have drawn much attention due to ultrahigh power densities with quick charging and discharging rates. In this report, A-site Nd-doped (1-x)BiFeO3-xBaTiO3 (x = 0.2–0.45) relaxor ferroelectric ceramics with superior storage efficiencies were prepared with 0.1 wt% MnO2 additive. Energy-storage efficiency (η) increases from 63.7% to 89% at 190 kV/cm as BaTiO3 increases accompanied by recoverable energy densities (Wrec) in the range of 2.5–2.7 J/cm3. The energy-storage performance persists thermally stable up to 125 °C. The superior storage efficiency is associated with growth of the cubic Pm-3m symmetry and the core-shell structure with increasing BaTiO3 content. The formation of nanocluster/nanomosaic structure also plays an essential role as a barrier in suppressing the long-range polarization order. This work provides a design of binary rare-earth doped BiFeO3–BaTiO3 dielectric ceramics for thermally stable and high-efficiency electrical energy storage.

Unusual crystal structure evolution, multiple phase boundaries and phase coexistence in (1 - x)Ba(Cu1/3Nb2/3)O3-(x)PbTiO3 perovskite solid solution.

Exploring the functionalities of materials requires a profound understanding of the crystal structure. In this paper, room temperature crystal structures of a new solid solution (1 - x)Ba(Cu1/3Nb2/3)O3-(x)PbTiO3 have been investigated in the entire compositional span and different crystallographic phases and phase coexistence regions have been discovered. The confirmation of the symmetry of these crystal structures has been done with the help of Rietveld analysis of the high-resolution XRD data. Despite both the end components, Ba(Cu1/3Nb2/3)O3 and PbTiO3, having tetragonal (P4mm) symmetry, new cubic and monoclinic phases have been discovered for the intermediate compositions with multiple phase boundaries. The composition region 0.05 ≤ x ≤ 0.55 exhibits a cubic crystal structure and increasing PbTiO3 concentration to 0.62 results in a unique coexistence of two tetragonal phases with different tetragonalities. This transformation is mediated by coexisting cubic and tetragonal phases, for 0.59 and 0.60. The crystal structure of the solid solution later transforms into coexisting monoclinic and tetragonal phases for a wider compositional span i.e., 0.65 ≤ x ≤ 0.85. This composition region is very fascinating, as two phenomenologically different monoclinic structures have been observed in it. Finally, a tetragonal phase at x = 1 is achieved through the mediation of two coexisting tetragonal phases, for the region 0.85 < x ≤ 0.975. The evolution of different crystallographic structures and the coexisting phases are critically comprehended using the variations in the lattice parameters and unit cell volume. The presence of multiple phase boundaries spread across a wide range of compositions makes this solid solution very intriguing and a viable choice for exploring different properties with compositional tuning.

Modulation of polar dynamics with oxygen vacancies in Zn doped BaZr0.1Ti0.9O3

Zinc modified barium zirconium titanate ceramics have been fabricated by the solid-state reaction method. Crystallographic analysis shows that the ceramics exhibit tetragonal crystal structure with P4mm symmetry. The polar behavior of Zn doped BaZr0.1Ti0.9O3 [BZT] differs from the pure BZT compound, as observed from ferroelectric analysis. As a result of doping, the P-E loops become pinched and linear in the low field region as well as P-E loop characteristics transformed from single hysteresis to double hysteresis behavior. Double hysteresis behavior emerging in BZT ferroelectrics validates the leading characteristic of defective dipoles. The defect dipoles provide restoring force to the spontaneous dipoles and ease the recovery of domain towards its original orientation. To validate the role of defects dipoles in the synthesized ceramics, we performed P-E hysteresis measurement under field cooling protocol. P-E loops of field cooled doped-ceramics transformed into single hysteresis curve and shifts on field scale, which further confirms that the double hysteresis feature is associated with defects dipoles rather than antiferroelectric ordering. The normalized entropy curves, ΔS(E,T,x)/ΔSmax(E,TC,x), for x = 0–6%, follow the scheme of master curve with two reference temperatures and consistent with second-order phase transition theory. The dielectric spectroscopy and Arrott plot approach collectively reveal that Zn doping causes sharpening of Landau free energy profiles and doping increases the depth of double-well potential and lowers the polar dynamics. The room temperature energy storage efficiency (η∼83,x=6%) of BZT is significantly modified. Our study reveals that the interplay between ferroelectric dipoles and point defects opens a novel route toward the realization of efficient energy storage performance.

Evaluation of rare earth substitution in the structural and magnetic properties of the REBa1-xSrxCuFeO5 (x = 0.0, 0.25 and 0.5) system

YBaCuFeO5 double perovskite has received attention because it is one of the few materials with the possibility to be multiferroic at room temperature. It is possible to explore such properties by partially replacing yttrium (Y) with rare earth elements (RE) or varying the chemical pressure of the system by replacing Ba with Sr. The synthesis and characterization of the new materials with the formula REBa1-xSrxCuFeO5, using the solid-state reaction method is reported. The results show that RE substitution allows the growth of single-phase materials, with tetragonal structure and symmetry P4mm. The morphological results evidence a consistent morphology by using the synthesis method. The magnetization curves in a temperature range of 50 to 380 K show, for the RE = Y system, a magnetic phase transitions at high temperature (<250 K). However, no magnetic transition was observed for compounds doped with RE = Ho, Dy, and Gd.

Structural, dielectric, ferroelectric and electrical behavior of (Bi0.5Ba0.25Sr0.25)(Ti0.25Mn0.25Fe0.5)O3

The Rietveld refined X-ray diffraction pattern of (Bi0.5Ba0.25Sr0.25)(Ti0.25Mn0.25Fe0.5)O3 sample synthesized through the high temperature mixed oxide solid state route confirms the tetragonal (space group: P4mm) symmetry. The scanning electron micrographs clearly explain the morphology of the sample. Temperature and frequency dependent dielectric parameters as well as the PE-hysteresis loop explain the validity of Curie Weiss law and ferroelectricity present in the material below the TC. The non-Debye type of relaxation, effect of grain and grain boundary on impedance is illuminated by the impedance analysis. The Field-leakage current (JE) characteristics revealed the space charge limited and Ohmic-type conduction process occurring in the material.

Use of cubic structure with primitive nanochannels for fabrication of free standing 3D nanowire network of Pt with Pm3m symmetry

In this work, we developed a lipid mixture based on phytantriol / polyoxyethylene surfactant (Brij-56) that forms a Im3m symmetry bicontinuous cubic phase based on the Schwartz primitive surface (Q II P ), from which we templated highly ordered 3D nanoporous platinum with a novel ‘single primitive’ morphology (Pm3m symmetry). The Q II P template phase is obtained by incorporation of 17.5% w/w Brij-56 (C16EO10) (a type-I surfactant) into phytantriol under excess hydration conditions. Phytantriol alone forms the double diamond Q II D (Pn3m) phase, and in previous studies incorporating Brij-56 at different compositions the cubic phase maintained this morphology, but increased its lattice parameter; mesoporous metals templated from these Q II D lipid templates all exhibited the ‘single diamond’ (Fd3m) morphology. In contrast, the current paper presents the availability of our Q II P cubic phases to template nanoporous materials of single primitive Pm3m morphology via chemical and electrochemical methods. To explore the structure porosity and morphological features of the templated Pt material, x-ray scattering and transmission electron microscopy are used. The resulting 3D nanoporous Pt materials are found to exhibit a regular network of Pt nanowires of ∼4 nm in diameter with a unit cell dimension of 14.8 ± 0.8 nm, reflecting the aqueous network within the Q II P template.

Stability of rhombohedral structure and improved dielectric and ferroelectric properties of Ba, Na, Ti doped BiFeO3 solid solutions

A study of the (1-x)BiFeO 3 -(x)Ba 1/2 Na 1/2 TiO 2.75 (BFO-BNT) solid solutions obtained using the solid state reaction method, for different molar relative concentration of Ba 1/2 Na 1/2 TiO 2.75 in the 0.0 ≤ x ≤ 0.12 composition range, is presented. The crystal structure and the dielectric and ferroelectric properties are studied in detail. Results of the Rietveld refinement of the X-ray diffraction data demonstrate that the system is single phase with R3c symmetry up to x = 0.09 while for x = 0.12, a small quantity of a secondary phase with P4mm symmetry appears. Scanning electron microscopy demonstrates that BNT presence promotes grain growth resulting in larger grains. Raman spectroscopy shows that, with increasing x, some of the A and E Raman modes slightly reduce their intensity while shifting in frequency, evincing the structural changes caused by the Ba, Na, and Ti incorporation on the BFO lattice. The X-ray photoelectron spectroscopy study confirms the successful substitution and gradual structural distortion in the samples. The improvement in dielectric properties with increasing BNT concentration can be attributed to stable dipole moment formation. Compared with pure BFO ceramics, doped BFO samples exhibit remarkably enhanced ferroelectric properties.